HIV seroprevalence and seroincidence rates have reached catastrophic levels among young Black men who have sex with men (YBMSM). Black MSM are also tested less frequently for HIV and are less likely to be aware of their HIV-positive serostatus than other MSM. Clearly, HIV prevention methods currently used to reach YBMSM are not effective. The Mpowerment Project is the only community-level HIV prevention intervention developed specifically for young gay/bisexual men that has been shown to have evidence of effectiveness in reducing the proportion of men reporting unprotected anal sex. However, Black CBOs are reluctant to implement the Mpowerment Project until it has been adapted to the context of YBMSM's lives and its efficacy in reducing rates of unprotected sex and increasing HIV antibody testing rates have been established Therefore, the developers of the Mpowerment Project have spent five years tailoring the intervention to the socioeconomic, cultural, and social context of YBMSM's lives through formative, qualitative research with HIV-positive and HIV-negative YBMSM and through collaborative research with three Black CBOs and two Boards of Cultural Experts, comprised of Black gay/same gender-loving men. The primary goal of this project is to test the efficacy of the tailored Mpowerment Project in reducing sexual risk behavior and increasing testing among YBMSM. The specific aims of this study are: (1) To implement the tailored Mpowerment Project for two years in one community (Atlanta, GA), and use a second community (Houston, TX) as a control that will not receive the intervention;(2) To conduct cross-sectional surveys of YBMSM before and after the intervention in both communities using venue-based day-time-space sampling to determine the efficacy of the intervention in: (a) reducing the proportion and frequency of sexual behaviors that are likely to transmit HIV, including reducing the number of sex partners;(b) increasing the proportion of men who know their HIV serostatus;(c) modifying psychosocial mediating variables that may be causally related to HIV risk reduction;and (d) changing psychosocial factors that are indicators of positive mental health and well-being;(3) To conduct process evaluations of the intervention to assess how the tailored Mpowerment Project is implemented and to assess the perceptions of the project at both the individual- and community-level. We will also look for changes in sexually transmitted infection rates in both communities.